Context. A significant fraction of the high-redshift galaxies show strong
emission lines. For redshifts , most known galaxies belong to this
class. However, so far not much is known about the physical structure and
nature of these objects.

Aims.Our aim is to analyse the emission in a
sample of high-redshift UV-continuum selected galaxies and to derive the
physical conditions that determine the profile and the line
strength.

Methods. VLT/FORS spectra with a resolution of R≈ 2000 of 16
galaxies in the redshift range of to 5 are presented. The
observed profiles are compared with theoretical models.

Results.The
lines range from pure absorption ( Å) to strong emission
( Å). Most emission lines show an asymmetric profile, and three
galaxies have a double-peaked profile. Both types of profiles can be
explained by a uniform model consisting of an expanding shell of neutral and
ionised hydrogen around a compact starburst region. The broad, blueshifted,
low-ionisation interstellar absorption lines indicate a galaxy-scale outflow
of the ISM. The strengths of these lines are found to be determined in part
by the velocity dispersion of the outflowing medium. We find star-formation
rates of these galaxies ranging from = 1.2 to 63.2 yr-1
uncorrected for dust absorption.

Conclusions.The emission strength of our
target galaxies is found to be determined by the amount of dust and the
kinematics of the outflowing material.

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